NTSB flags safety concerns at 68 bridges following Key Bridge investigation

The risk of collapse for the Francis Scott Key Bridge was nearly 30 times higher than the acceptable risk threshold set by the American Association of State Highway and Transportation Officials (AASHTO)—yet it took a catastrophic vessel strike to reveal the danger. Now, 68 other U.S. bridges face unknown levels of risk, sparking urgent calls for action.

The National Transportation Safety Board (NTSB) released these findings in its Marine Investigation Report as part of an investigation into the deadly bridge collapse on March 26, 2024. The board found the collapse was due in part to the Key Bridge’s outdated design, increased vessel traffic and the larger size of modern ships. The risks placed the bridge’s annual frequency of collapse nearly 30 times above AASHTO’s acceptable threshold for critical bridges.

The Key Bridge, built in 1977, lacked modern protections and had never had any prior vulnerability assessment conducted. The 68 other bridges mentioned in the report that face an unknown risk were all built before 1996.

NTSB chair Jennifer Homendy said in a press briefing that if the Maryland Transportation Authority had conducted a vulnerability assessment, it could have identified the bridge’s heightened risk and taken action to prevent the collapse.

The NTSB is urging the Federal Highway Administration, Coast Guard and Army Corps of Engineers to form an interdisciplinary team to evaluate and mitigate risk. The board has issued an urgent call to action for 30 bridge owners, in particular, requesting they assess their collapse risk and implement safety measures if necessary.

“Today’s report does not suggest that the 68 bridges are certain to collapse,” the NTSB said in a press release. “The NTSB is recommending that these 30 bridge owners evaluate whether the bridges are above the AASHTO acceptable level of risk. The NTSB recommended that bridge owners develop and implement a comprehensive risk reduction plan, if the calculations indicate a bridge has a risk level above the AASHTO threshold.”

The 30 bridges in need of risk assessment can be found in:

California (7): Richmond-San Rafael Bridge, Carquinez Bridge, Benicia-Martinez Bridge, Antioch Bridge, San Mateo-Hayward Bridge, Coronado Bridge, Golden Gate Bridge
Louisiana (6): Huey P. Long Bridge, Greater New Orleans Bridge, Israel LaFleur Bridge, Crescent City Connection Bridge, Hale Boggs (Luling) Bridge, Horace Wilkinson Bridge
Delaware (3): Summit Bridge, Saint Georges Bridge, Reedy Point Bridge
Florida (2): Sunshine Skyway Bridge, Napoleon Bonaparte Broward Bridge (Dames Point Bridge)
Maryland (2): William Preston Lane Jr. (Bay) Bridge (Eastbound), William Preston Lane Jr. (Bay) Bridge (Westbound)
New York (2): Verrazano-Narrows Bridge (Eastbound), Verrazano-Narrows Bridge (Westbound)
Texas (2): Sidney Sherman Bridge, Rainbow Bridge
Georgia (1): Talmadge Bridge
Michigan (1): Mackinac Bridge
New York / New Jersey (1): George Washington Bridge
Oregon (1): Astoria-Megler Bridge
Washington (1): Lewis and Clark Bridge